Generally, a stocker apparatus is used, for example, when resin molded articles such as resin gears are manufactured by a resin molding apparatus. The stocker apparatus loads on an empty tray existing therein the molded articles manufactured by the resin molding apparatus and then carried by an external carrier such as a robot or the like, and stocks many trays, which are loaded with the molded articles, stacked one on the other.
A currently available stocker apparatus includes a first tray stock section where empty trays are stocked and a second tray stock section where loaded trays are stocked. In the first tray stock section, many empty trays are stocked, stacked one on the other. The stocker apparatus further has lifting and lowering means which lift and lower the trays existing in the first tray stock section and the second tray stock section, and carrier means for carrying the loaded trays to the second tray stock section.
The stocker apparatus is provided in a manner to be open to the outside with the trays and the molded articles being exposed to an external atmosphere.
Incidentally, stocker apparatuses described in documents include one described in, for example, Japanese Padent Laid-open No. Hei 6-9016, though it is of a different type. However, there is no other document known at present which describes a stocker apparatus of the above-described type in which many trays are stacked one on the other. Note that the stocker apparatus is also called as a stock system or a stocker.
Incidentally, in the current stocker apparatus, the empty trays and the loaded trays are stacked in a manner to be open to the outside. In addition, when the resin molded articles are manufactured, a crusher that crushes a runner (unnecessary portion) separated from the resin molded articles is often installed, creating an environment containing much dust.
For this reason, if the stocker apparatus is exposed to the atmosphere containing much dust such as in a factory, much dust adheres to a tray and a loaded tray stacked at the uppermost tier. If dust adheres to the aforementioned tray and the loaded trays, the dust actually adheres to the manufactured molded articles, and the adhesion of dust is not preferable from the aspect of sanitary especially when the molded articles are containers for food (for example, egg cases and so on made of resin).
Further, adhesion of dust to, for example, precision electronic components and so on will cause defects. For this reason, the molded articles for precision products sometimes need to be cleaned sufficiently prior to being assembled as products.
Besides, downsizing of the stocker apparatus itself has not been under consideration since the current stocker apparatus cooperates with large resin molding apparatus and external carrier, and therefore even a large stocker apparatus is acceptable. As a result of this, the stocker apparatus generally occupies a large space. This brings about a problem of installation of a stocker apparatus not being allowed when installation space is limited.
Furthermore, the current stocker apparatus is expensive relative to its function of simple loading. Stocker apparatuses may be, for example, as expensive as a resin molding apparatus and, in some case, more expensive than a resin molding apparatus. In a field of resin molding, however, the stocker apparatus is handled as an apparatus attached to the resin molding apparatus, and accordingly the function and cost are sufficiently examined for the resin molding apparatus, whereas the stocker apparatus has been employed without sufficient consideration even if it is slightly expensive.
The present invention has been developed based on the above-described circumstances, and its object is to provide a stocker apparatus capable of loading products on trays with the products and trays kept clean. In addition to the above-descried object, an object of another invention is to provide a stocker apparatus capable of reducing in size and cost.